You could download the Debian of package libstdc++6 for Xenial at link http://packages.ubuntu.com/xenial/libstdc++6 and installed it using dpkg -i (reference: https://askubuntu.com/questions/777803/apt-relocation-error-version-glibcxx-3-4-21-not-defined-in-file-libstdc-so-6).

Error while loading shared libraries: libgconf-2.so.4

Try install libgconf-2-4 first.

NSS out-of-date

If you recieve following error when launch Typora:

[7465:7499:0911/174740.042852:FATAL:nss_util.cc(632)] NSS_VersionCheck("3.26") failed. NSS >= 3.26 is required. Please upgrade to the latest NSS, and if you still get this error, contact your distribution maintainer.
Aborted